I was once an avid mineral collector and one of my favorites was clear Fluorite. I recently picked up the two pieces below at a show but not just because they have clear Fluorite, they also have fossils in them. They come from a quarry in Walworth, NY that mines the Lockport formation (Silurian, Gorstian stage). The Lockport is a very hard, dolomitic limestone that is used as road gravel. The rock may be hard but it develops cavities from pressure solutions and ground water dissolving it away bit by bit. Within the cavities created by this process minerals can precipitate. Sometimes the cavities result from a fossil being dissolved away too.
This first piece has a large rounded cavity with some cubes of clear Fluorite. I can't be sure but some of the calcite druze looks like it is patterned after a bryozoan.
On one side of the piece is this series of cavities that look like some sort of coral.
The second piece has a much more obvious fossil coral visible just below the mineral bearing pocket. It looks like a type of Favosite.
The Fluorite cubes on this piece are hidden deep in the pocket and are not easy to see. Were I strictly a mineral collector I would likely trim this piece down a bit more so that the Fluorite was more visible.
If you like mineral and want to see what else can be found in the Lockport Dolomite, head on over to the
New York State Academy of Mineralogy website to see more.
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